Controlling device for heat transference in refrigerators



June 17, 1930. BRUEHL ET AL 1,764,194

CONTROLLING DEVICE FOR HEAT TRANSFERENCE' IN REFRIGERATORS Filed April 4, 1927 3 Sheets-Sheet l I I I 27 g 21 O 16 4 1 r T 26 i? C) O Z8 28 Y m I INVENTORJ A TTORNE Y5 June 17, 1930.

L. BRUEI-IIL Er AL ,764,194

CONTROLLING DsvIcs FOR mm TRANSFERENCE IN REFRIGERATORS Filed April 4, 1927 5 Sheets-Sheet 2 x Y INVENTORS lamzzggfimeilmzlmflabkri A T T ORNE KS Jun: 17, 1930. B LET AL 1,764,194

CONTROLLING DEVICE FOR HEAT TRANSFERENCE IN REFRIGERATORS Filed April 4, 1927 3 sheets sheet 3 IN V EN TORS A T TORNEYS.

mentsuch as the conraomme nnvrcr. ron HEAT ramsraamvcatm maremroas Application filed April 4,

This invention relates to means for regulating the temperature of a refrigerator or cooling-chamber containing a cooling eleevaporator of ing machine or If the doors of a refrigerator remain closed for a long time and consequently only a small amount of heat is admitted to the interior thereof, there-will be a tendency for the temperature therein to fall to too low a level. This condition is especially likely to exist if the outside temperature is relatively low. It is not desirable to have the temperature in the refrigerator too low inasmuch as food therein might be frozen or made too cold for table use.

e main object of our invention is to provide an automatic temperature control for the refrigerator, which control is located entirely within the refrigerator andhas no communication with the outside thereof.

A clear idea of the invention may be-ob tained by c h1sidering the temperature conditions and the path of the air currents in refrigerators. The transfer of heat between the cooling element or evaporator and the air is effected by conduction and radiation and the air around the evaporator is cooled and then flows down due to its greater speis replaced by warmer air of the compartments, thus causing circulationof the air past the cool ing element. Assuming the evaporatortemperature to be constant, the force tending to causecirculation of the air depends upon the average temperature in the refrigerator and would be zero if-the interior temperature of the refrigerator chamber and-the temperature of the evaporator were the same. Such a condition is never reached in a continuously working refrigerating machine except in the event that the refrigerating machine I stops. In an absorption machine of the intermittent t e said force tending to cause circulation o the air goes down to zero and even becomes negative during the boiling period of the machine.

The force tending to produce circulation of theair is not only a a refrigerat-' an element cooled by brine.

function of the temperature as already mentioned but is also- 1937. Serial No. 180,749.

a function of the amount of heat transmitted through the air of the refrigerator and between the evaporator and the outside -.-of the refrigerator, such functions being interdependent; This force depends also on the outside or room temperature in that a high outside or room temperature increases said force and a low outside temperature decreases said force assuming that the evaporator temperature is constant. This would mean that the temperature in the refrigerator would vary automatically. to a predetermined value without using any control, and

this result might be obtamed'by structural means only if it were possible to keep the evaporator at a constant temperature. It is, however, practically impossible to obtain such a result by simple means because the temperature of the evaporator is influenced y a number of outside factors which var necessary to provide other and automatic means to control such force tending to produce circulation of the air.

Our invention may be carried out in different ways, as, for example, by providing automatic means for varying the heat trans- IIllSSlOIl surface of varying the effective size of the air flow pas- 1 the evaporator, or by sage. Other objects and advantages will be pointed out hereinafter or Willbe apparent from a consideration of the embodiments illustrated in the accompanying drawings. It is to.be understood that these drawings are to be considered in an than in a limiting sense.

In the drawings:

Fig. 1 is a diagrammatic View a refrigerator inventlon;

illustrating embodying one form of the illustrative rather y considerably and 1t 1s therefore particularlyv Fig. 2 is a detail view, partly in section,

of thestructure shownin Fig. 1, a

Fig. 3 is a detail view of the connection between a wing or vane and the Wing-shifting means;

Figs. 4 to '11 are views illustrating other forms of the invention.

In Fig. 1, the invention is illustrated as applied to a refrigerator box or compart- 0 P 2 element 11 may take up ment 10 which contains in the upperright hand portion thereof a cooling element 11 which may be an evaporator of a-refrigerating a paratus of which the other parts are outsi e of the compartment 10., The cooling element may be s aced from the wall of the box 10 and may 4 compartment 12 formed by a bafiie 13 having upright and horizontal portions spaced from the box 10 so as to provide an entrance 14 at the top of the compartment 12 and an opening or exit 15 beneath said cooling element 11. Warm air in the refrigerator rises to the top thereof at the'left of the bafiie 13,

passes through said entrance 14, downaround. the cooling element 11 by which it is .cooled, and then due to its greater specific gravity passes out through the opening 15 into the lower part of the box or comheat from objects in the lower part of the refrigerator, rise again at the left of the bafiie 13, and go through the same cycle as before.

Continued circulation of the airthrough the openings 14 and 15 may result in reducing the temperature in the box 10 to too great an extent and according to the present invention this condition may be prevented by automatic control means located in the box 10. To this end there is provided at one edge of the openin 15 a movable wing or bafiie 16 which by suitable means is swding'to decrease or stop the flow of air through the compartment 12 when the temperature becomes too low in the box and is swung to permit or increase the flow when the temperature becomes too high. When the current of air through the compartment 13 is shut off, the air in said compartment is substantially dead and exerts a higher resistance to the transfer of heat from thecooling element 11 to the total quantity of air in the box 10. Obviously. the bafiie 13 may be connected with the evaporator itself or may be attached to the refrigerator box.

It is essential, however, that the coefiicient of heat transmission be changed considerably to cause the cooling effect of the evaporator on the refrigerator box to change insuch a manner that the temperature will have a ris-v ing tendency or at least keep constant and not lower further. When the opening 15 is closed, the air is forced to circulate outside of the compartment 12 as indicated by the downwardly extending arrows 17 and the cooling effect .of the element 11 is exerted through the air space in the com artment 12 and t rough the insulating bafiib 13-which must have a certain heat leakage to avoid too rapid oscillation of the control and to obtain smoother operation.

If the entire heat flow from the'contents of the refrigerator box to the evaporator 11 through the baflie 13 is' reater than the flow e to the part of the of heat from the outsi positioned within a artment 10. The cold air from the cooling- 24 is acasing or refrigerator outside of the baflie 13, the flow from the outside to the evaporator compartment need not be considered because it would have no influence upon the food compartment as the temperature would sink 'in any event, but if said flow of heat 'from the outside of the compartment 12 to the evaporator is less than the flow coming from the outside at the temperature at which the opening 15 has been closed, the openin 15 must be opened again, The extreme y cold air in com artment 12 then flows to the lower part of t e refrigerator box 10 and the opening 11 is again closed. If the control means 15 es cial y sensitive,- that is, if a difference 0 a few degrees in temperature is sufficient to open or close the opening 15, the control will make oscillations which will be avoided if both flows of heat are about the same, in

other words, if the resistance in baflle 13 is about the same as the resistance in the walls of the refrigerator box.

Oneform of automatic controlling means for the movable baffle 16 is indicated in Fig. 1, and in greater detail in Figs. 2 and 3. The bafiie 16 is provided at one edge with a member 18 having an internally threaded socket into which is fitted a screw 20 provided with a head suitable for actuation by a wrench. Mounted on the shaft or screw 20 is a pinion 21 having a peripheral groove in which engage on opposite sides two rods 22 and 23 having rack bar portions. One is threaded into a member 24 and adjustably locked therein by-nuts 25. Fixed in said member rod 23. The rod 23 extends into the tube 26 and is secured thereto at the lower end by suitable means such as solder.: The rod 23 and the tube 26 are of metal and with such different coefiicients of heat expansion-that, as the temperature rises, the upper end of the rod 23 moves out of the upper end of the tube and swings the baffle or wing open position. As the temperature falls, the rod 23 will contract more rapidly than the tube or casin moved towar s the closed position.

If the pinion 21 were held absolutely against rotation with reference to the pivot screw. 20 it would he very difiicult to agjust uch the control after installation thereof.

difficulty is, however, eliminated by the arrangement shown in Fig. 3. The screw 20 is held in the member 18 a inst loosening by a lock nut 27 and to hol the worm gear 21 yieldably in position springwashers .28 are placed 'on opposite sides of the worm gear 21. This arrangement enables easy rotational adjustment between the wing 16 and the pinion 21, inasmuch as the wing and pinion are held together frictionally.

In the embodiment of of wings or-bafiies 30 w ch may be operated tube 26 which guides the 16 towards its' the automatic con trol illustrated in Fig. 4, there are a number 26 and the wing 16 will be v It may be riveted to the bar definite cross-section for the simultaneously and are provided with arms 31 pivoted at 32 to a supporting bar 33 held in position by suitable means, such as screws. A rod or bar 35 is mounted parallel to the bar 33 and is pivoted at points 36 to said arms 31. A U-shaped bi-metallic strip37 has. its ends connected to the ends of 33 and merely the bar 35. The pivots 32 are so in respect to the centers of gravit wings that the abut against located of the wings tend ,to force the rod to the left against the end of the thermostatic or bimetallic strip 37 which responds to temperature changes in the re- :fri erator.

he bi-metallic strip 37 is so arranged that 'an increase in the temperature of the box acts to close the'open end thereof thus permitting the wings 30 to drop down, anda decrease in temperature acts to spread apart the ends of the U-shaped member and thereby to raise said wings 30to effective or closing position. It will be apparent that for definite intermediate temperature the wings will take definite positions intermediate their open and closed positions thus providing a passage of air through the openings between the wings. The member 37 may be so arrangedthat at a certain predetermined temperature of the the wings cooperate with each other to close the openings, the lower end of each wing to the le coming in contact with the upper end of each wing to the right.

The wings of the control device illustrated .in Fig. 4 open and close gradually in response to changes in temperature. In Fig. 5 however, there is disclosed a structure by which a snap action in opening andQclosing the wings 30 is obtained. This control is sub '1 stantially the same as that illustrated in Fig. 4 except that the wings are normally in raised position and may be swung downwardly to closed position. In this arrangement wings 3O are provided with downwardly projecting arms 31 pivoted'at 32 or 37 is provided with a hook or lug 40 having lost motion connections with the end of the rod 35.

en the temperature decreases the U shaped member. opens at its top and until the pivots of the arms 31 on the rod '35 pass beneath the pivots on the rod 33 the wings will be overbalanced and fall to closed position. ey remain closed until a change in temperature in the reverse direction moves the pivots beneath the centers of gravity of the wings and a slight further movement of l the bar 35 causes a snap action to full open position. When the wings are thus opened, 0

the temperature of the box will start to rise. The play between the parts may, however, be so arranged that the wings remain closed during a rise of temperature to a certain number of. degrees, say 45, the Wings then bars 33 and 35. l

y according to the to bars 33 and 35. One end of the oi-metallic memb opening gradually and the dead center position being passed at a higher temperature, say 50, the wings then snapping to'their limiting positions to open completely the space controlled thereby. v

he snap action just described has the same effect as the heat leakage of baffle 13 in Fig. 1, that is, of reducing the operation of the control as much as possible. This means that above temperatures which for example, the control allbetween 38 and 45 are given merely would not work at Fahrenheit as the temperature increases, and

between 50 and 43? as the temperature de- In the hereinafter described controls, the

coeflicient of heat transmission is regulated but this regulation is valuable principally in the limiting conditions of thecontrol, that is, when the control is closed or I opened. Whenthe control is closed the co'efiicie'nt of heat transmission is based upon the influence of the air space in compartment 12 and of the baffle 13 incl lding all surface resistance. When'the contro is opened the surface resistance of the evaporator determines the coeflicient of heat transmission. If the snap action is employed, it may be possible to con trol'the coefiicient of heat transmission only when the control has only two positions, either open or closed. Such a control is not, however, of special interest in that it would require additional members and would be more expensive.

The controls illustrated effective in all of the intermediate positions as well as for the end positions. cross-section of the air currentis bythe control the air is forced onger in compartment 12 so that the air temperature sinks crease of the an temperature also decreases diminished the diiierence between theair temperature and the evaporator temperature so that a smaller amount of heat passes from the air to the coolin element or evaporator, thus controlling t e temperature of the air indirectly. The decrease of temperature in the refrigerator static control serves to decrease the air temperature incompartment 12 relatively more, so that the flow of cold from or of heat to the evaporator is diminished, that is, the control interferes withthe velocity of air circulaticilnand thus obtains the desired efiect.

frigerator box may also be controlled by ensurface of the cooling device or evaporator. ne arrangement for obtaining this result is 'llustrated in Fig. 6 in which there is s own a wall 42 of a cooling unit. Wings f heat conducting material are pivoted at 4 on a fixed bar 45 to be swung .to and from contact with the wall 42 by means of a compartment which affects the thermo-' e regulation of temperature in the re-*v arging or dimenishing the heat transferring I I bar 46 wings 43 is shifted to move tor box,

L shaped bi-metallic the coolihg wall 42,

place.

. tact with the surf arallel to the bar andpivoted'at 47 to t e wings 43. The movement of the to and from contact with the wall 42 may be effected .by suitable thermostatic means such, for example, as disclosed in Figs. 4 and 5. When the temperature of the box decreased below a certain point, the bar 46 all of the wings 43 away the heat transfer taking from the wall 42,

a minimilm surface only,

lace then through 1n other words, the surface of the wall 42.

After the box temperature has risen to a predetermined! degree the wings 43 will again be moved into contact with-the wall 42 and the heat transferring area will be increased by addition of the area .of the wings 43 to that of the wall 42. The wall 42 may be cooled by-direct contact with liquid refrigerant or rine or any other medium between the evaporator or cooling element and the wall 42.. The heat transfer between the cooling element and the air in the refrigerais obtained by the wall 42.

In Fig. 7 there is shown an arrangement adapted for the same purpose as the arrangement disclosed in Fig. 6 but in whichU- strips 48 are secured'to a second housing 49 outside of the wall 42 of the cooling element. With this arrangement a decrease box temperature causes withdrawal of bi-metallic strips from the surface ofthe wall 42 so that the heat transferring surface is diminished. A suitable increase in 4 box temperature causes the thermostatic strips 48 to contact again with the surface of thereby increasing the surfacethrough which heat transfer takes The bimetallic strips 48 may be so adjusted thatat a certain temperature, say 38 Fahrenheit, theywill move out of conace of the cooling element. At all temperatures below this critical temerature the strips 48 will be out of contact with the wall 42, and also at temperatures the shifta le members the cooling tallic strips 48 above 38 Fahrenheit the strips will be in good thermal contact with the surface of the wall 42. Special care must be taken that in the arran ements illustrated in Figs. 6 and 7 be kept from freezing tight to'thewall of the cooling element. In accordance with the construction shown in Fig. 7 it may be arranged so that the strips move constantly to and from the wall 42 of element thus tending to prevent such freezingaction. Figs. 6 and 7 are top views and it 'will be seen that the air as cooled passes freely downward between the fins or wings 43 in one case and the bi-mein the other from the upper to the lower part of the cooling element.

Fig. 8 illustrates an arrangement which is circular instead of'straight as in Figs. 6 and 7 and which differs from Fig. 7 in that the thermostatic metal strips are in dead air danger of the walls. In this form, a cooling element or evaporator 52 is separated byia dead air space from an outer casin 53 w ich may be enclosed in any suitab e medium 54 through which the cooling effect may be transmitted .to a compartment 55 or to a room. The medium 54 may consist of brine in a tank or may be a block of aluminum which has high thermal conductivity, and the com artment 55 may be used for any articles to for ice trays. Supported on the casing 53 the freezing of the strips. tight to I cooled or and inside thereofare U -shaped thermostatic 7 metal strips the medium strips 56 are retracted from the cooling element 52 so that the coolin effect transmitted to the casing 53 is con'si erably decreased inasmuch. as the transfer of heat or cold must pass between the high resistance of the dead air between the outer and inner casings.

56. When the temperature of.

When on the other hand the temperature rises to a certain point the thermostatic strips 56 again contact with the casing of the evaporator 52 and the cooling effect is increased. As a result of the fact that the air between the outer casin 53 and the cooling element 52 is substantia ly still or dead, no

condensation from humid air settles in this 1 space and consequently here is no danger that the thermostatic strips will freeze to the cooling element 52. I InFigs. 9, 10 and 11 the same desired result is obtained by diiferent'arrangements in which the cooling element or evaporator may be brought into contact to a greater or less extent with the wall of an outer casing or re moved entirely from contact therewith to vary the amount of heat transference taking place through the wall of the outer casing.

In Fig. 9, the evaporator or cooling element 57 is provided at one side with a projection 58 fulcrumed in a notch of an outer casin 60 54 falls to a certain point, theand is connectediat its opposite side wit a thermostatic element 61 by which it is moved back and forth about its fulcrum at said notch. At one side the outer casing 60 has a portion of the same curvature as the cooling element 57 and at the other side has'a portion of greater length and of a curvature of greater radius than the cooling element so that the cooling element upon swinging in one direction will be brought into contact with and fit in the portion of the sgme curvature therewith but when swung awa heldiout of contact th the wall ofthe casing 60. The thermostatic element 61 includes a rod 62 attached to the cooling element 57 at the opposite side from the projection 58 and also connected with a member 63 secured to a tube 64 attached at its other end to a rod 65 havin a slidable fit therein. This rod 65 .has a di erent coeflicient 'of heat expansion from the tube 64 and is adjustably secured at its outer end to a fixed lug 66 by means of nuts therefrom itmay be threaded on the rod 65 at opposite sides of the In 66. The casing 60 is surrounded b a suita le medium 68 through whichthe coo mg element may ,cool the material in a room or compartment 69. Th' ranged "and the material of the tube, 64 and the rod 65 is such that as the temperature increases above a certain point the coolin element 57 will be swung into contact wit the casing 60, and that w en the temperature falls to a sufficient extent the cooling element 57 will be moved away from the outer casing 60 its shown in Fig. 10, the cooling element is mounted within and spaced from the walls of an outer casing 71 of which the casing has one portion 73 of a certain radius larger than the radius of the cooling element and another part of still greater radius. ing element 70 and the casing is a conducting member or segment 72 contacting with the outside of the cooling element 70. This segment may be moved into greater or less the casing 71 or may be moved entirely out of contact'therewith. In this form the cooling element 70 be efiected. The rotation of the cooling element 70 may be effected by any of the thermostatic devices used in connection with the other embodiments of the invention.

larger portion 80 of a greaterradius. In this form, however, the cooling element 7 7 is slidably mounted between blocks or members 8].

for movement to and from the casing portion 7 9 and this movement is efi'ected by means including a U-shaped thermostatic stri 82 interposed between the casing 78 and t e cooling element 77 so that upon increase of temperature at the thermostatic strip 82 the cooling element 77 will be moved into contact from contact with the part 79 of the casing 78 thus controlling the cooling efi'ect transmitted through a medium 83 to a room or chamber Having thus described our invention, what we claim as new and desire to secure by Letters Patent is:

1. In refrigerating apparatus, a cooling element having a heat conducting wall memher, an auxiliary heat conducting member spaced from said wall member,

metallic strip mounted on one of said memb 'bers and responsive to increase of temperature to engage the other of said members and Between the coolb thereb increase the heat-transferring surface 0 said cooling element. 2. In refrigerating apparatus, a coo element having a heat conducting wall, a e parts are so arh eat conducting wall around the first-mentioned wall and enclosing an air space, bi-

.metallic means attached to one of said walls at the outer wall,-and responsive to decrease of temperature to disconnect said walls.

11 refrigerating element having a heat conducting wall, a. brine chamber including a second heat conducting wall enclosing an air space around said cooling element and separating said cooling element from said first-mentioned thermostatic means 'for making and g a thermal connection through said air space and between said walls, and a contamer for matter to be cooled by said brine.

4. In refrigerating a element havinga perip eral wall, a casing around said cooling element and ha a wall spaced from said peripheral wall, and thermostatic means responsive to changes of g temperature for thermally connecting or dis connecting said walls.

5. A container having a heat-transferring 1 y wall, heat-conducting bafiles extending longitudinally of said container and movable into contact with the wall thereof to increase the heat-transferring surface and to provide separate air spaces longitudinally of said container.

6. In combination, a cooling element hav- 7 ing a wall, a heat conduct ng wall spaced therefrom and parallel thereto, and a'pluthermostatic elements arranged in an annular thermostatic means for effecting thermal con- 10. In ducing cooling efl'ect and having a peripheral apparatus, a cooling paratus, a cooling combination, an evaporator for pro-' ifs" 6 meme;

' wall, a heat conductor encircling said evaporator, and a thermostatically operated movable member for varying the thermal con- I nection between the evaporator and the heat conductor.

11. In combination, an evaporator for pro dueing cooling effect and having a peripheral wall, a heat conductor encircling said evaporator, and a thermostatically operated movable member disposed between said evaporator and said conductor for varying the rate of heat transfer fromone to the other.

Signed at 20 Grand Ave., Brooklyn in the oountyof Kings and Stateof New York this first day of April, 1927. v

LAWRENCE BRUEHL. LUDWIG REICHERT. 

